One Very Special Reason
by Everlark-forever12
Summary: Cassie was your ordianary teenage girl with ordinary friends when tripping over can make you go into the land of OOO! Now she has to fight evil and find out what the One Very Special Reason she was sent there for! Join Cassie and Finn with friends on the journey! Finn/OC Book 1 of the One Very Special Reason trilogy! Reviews Please!
1. Chapter 1

**A/N**

**Hey Guys or Gals **

**I have written another fan fiction! It's about Adventure Time again because I absolutely love it.**

**I randomly came up with this one **

**But anyway on with the Fanfic!**

**Sharkpedofromverpets has helped me with this chapter too.**

**Disclaimer: I don't own adventure time! Pendleton Ward does**

**My OC's:**

**Cassie: Is 14 and has medium long brown hair with blonde highlights in it with blueish greenish eyes, she is like every other teenager is a little bit clumsy and immature. When you first meet Cassie she is shy and may seem un-approachable but when you get to know her she is out going and is not afraid to speak the truth. Her nickname is Snow.**

**Chelsea: Is Cassie's Best friend aged 14 and has shortish brown hair and is kind of exactly like Cassie except for a few minor differences. Her nickname which Cassie sometimes calls her is turtle lady. Chelsea loves playing games and hanging with Cassie especially if the "tricksters" are there as Chelsea and Cassie trick them back.**

**Scarlet: Blonde wavy hair down to her waist and his Chelsea's and Cassie's best friend also is like Cassie and is a fan girl same as Cassie and same age as Cassie, Grace, Montana and Chelsea. Usually hangs with them at school and doesn't like Grace and Montana as they used to be best friends with them but then had a huge fight when they were 10.**

**Grace: Is a friend of Cassie's and it is age 14 too but is mostly known with Montana as the "tricksters" because they always play tricks on her and sometimes Chelsea. Grace has Strawberry blonde hair that goes down to her waist. Like Cassie Grace is first off shy but when you get to know her she is a bit outgoing but still sometimes shy and goes to the same school as Cassie, Chelsea, Scarlet and Montana. Grace and Montana rarely talk to Scarlet after their fight when they were 10.**

**Montana: Is 14 years old too and best friends with Grace and friends with Cassie and Chelsea. She has dark brown hair which goes half way down her back and is the shortest out of all of them. With Grace she is known as the "tricksters" cause of their love of playing tricks on Cassie, Chelsea and sometimes Scarlet.**

**Please enjoy One Very Special Reason and please review**

**:D**

Chapter 1: 

**In one world then wait where am I!**

Cassie's POV

After waking up on a normal Sunday morning I decided to text Chelsea and see if she wanted to go to the shops to meet up because I knew the "tricksters" were going to be there and it was a boring Sunday after all and I had no home work either which is unusual.

After waiting for what it seemed forever but in reality it was only 5 minutes or less, Chelsea texted back sure I'm going to go to EB games too.

After getting dressed into a black tank top with a star on it and some jeans I walked to the shops to meet Chelsea.

At shops

After meeting up with Chelsea, we decided to go to EB games to buy some new games and found Scarlet in EB games.

After buying some new games Scarlet said "Hey Snow" a bit concerned and worried.

"Yeah what's wrong you kind of seem scared or worried about something" I said concerned of what Scarlet was worrying about.

"This probably sounds kind of stupid but I had a dream or kind of vision actually, that you randomly disappeared and ended up in a place that you were put there for one very special reason to stop major things from happening" Scarlet said not sure if it sounded silly but relieved to get that off her chest.

"Don't worry that sounds awesome like in Inuyasha, Kagome gets thrown into the feudal era of Japan" I said excitedly.

"Snow this serious listen" Scarlet and Chelsea said at the same time.

"Ok geez I know this is serious but seriously guys why someone would pick me to prevent major things from happening" I said

Why would someone pick me of all people to prevent major things from happening?

I mean I'm clumsy, immature and shy but then crazy and immature I mean see me at school.

"Oh no here comes the "tricksters" Chelsea said knocking me out of my daydream.

"Oh yeah, let's go somewhere else cause I am definitely not in the mood to hang out with them" I said kind of angrily because they are definitely really annoying sometimes.

"I just want a "trickster" free day for once in my life" I screamed in my head.

"Yep let's go" Scarlet said sick of Grace and Montana already although we haven't even talked to them.

As we ran away from Grace and Montana I of course tripped over but the last thing I saw was not the black and white tiled floor it was a blue swirling portal type thingy.

As I woke up my head was pounding like it was going to explode and I blacked out again but I didn't realize I was in a complete different world or time.

Finn's POV

When I was playing BMO I realized the sun was setting so I decided to go outside to sit and watch the sunset.

Unfortunately Jake had moved out already to move in with Lady Rainicorn as he now has his kids.

When I walked outside still locked in my thoughts I saw a beautiful girl with brown hair on the ground unconscious.

Although she was beautiful I thought she wasn't real because she looked human, but that's stupid because I'm the only human left in the whole of OOO.

The girl opened her beautiful bluey and greeny eyes and took in her new surroundings until her eyes landed on me.

Cassie's POV

As I woke up still feeling groggy I looked around at my new surroundings and I saw a boy around my age with a blue shirt and blue shorts with a bear hat on his head ( I have to say he looks kind of cute wait I didn't just say that!) staring at me so of course I screamed and I scream really loud I must say.

"Whoa calm down you're okay Im not going to hurt you" the mysterious yet cute boy said.

"I know this is not real so of course Grace and Montana must be up to their old tricks I fricking hate them sometimes! So come on come out Grace and Montana "I said really ticked cause Grace and Montana decided to be stupid again and trick me.

Why is it always me who they trick!?

I mean they haven't seen the **dark **side of me only a few people have.

At that time I stood up looking really ticked and no one messes with me when I'm angry because the last time someone did that at school I went crazy and nearly punched them although Scarlet and Chelsea heard me back before I snapped completely. Which when I snap completely in not so good.

"Whoa who's Grace and Montana I've never heard of them" the mysterious cute boy said looking at me concerned if I was going crazy.

"I'm not going crazy so don't worry but aren't I in 2013?" I said pretty sure I was still in 2013 but just in a other place or something thinking that Grace and Montana went really far to trick me.

"Nope you are in the land of OOO and I am OOO's hero and number 1 adventurer" the boy said.

"Okay? What's your name then hero?" I said already liking my new nickname for him.\

**(A/N I know Cassie used Marcy's nickname)**

"I'm Finn and who are you" Finn asked.

"I'm Cassie sorry about earlier it's just that the "tricksters" Grace and Montana always trick me and it really annoys me" I said embarrassed of how I yelled to Finn and I didn't even know his name then.

"Hey it's ok I'm used to it I get angry when one of my best friends Marceline the vampire queen tricks me" Finn told me relating how it's annoying when somebody annoys you.

"Oh that's bad" I said.

When I was talking to Finn I noticed that when he mentioned his friend Marceline I felt jealousy and I have only felt jealousy when my crush at school always hung out with girls

Third POV

Finn wouldn't admit it but whenever he looked at Cassie he thought she looked perfect. He felt this way about Flame Princess but they thought it would be better to be friends even though it hurt his heart he got over it. His heart broke when he got over Princess Bubblegum because she was his first real crush.

**A/N how was that chapter? It may not be my best writing as I wrote this a couple of months ago and my writing has gotten a lot better since then.**

**Hope you guys enjoyed it :D **

**PLEASE REVIEW!**

**Or you wouldn't like to meet us mwhahahahaha because together we are unstoppable **

**Cassie get outta here and you too Finn **

**Sorry they decided to bring everyone from OOO into my bedroom!**

**Anyway Please Review!**

**It makes me feel happy and I know that you enjoy the story**

**But enough of me ranting! **

**Hope you enjoyed it! (Sorry for the long authors note too)**


	2. Just a normal Day Again

**A/N**

**Yes it is the second chapter of One Very Special Reason**

**I hope you guys enjoy this chapter**

**Most of my fanfics now will not be edited by sharkpedofromverpets because I just want to publish them so I will be editing them**

**Sorry about any grammar mistakes!**

**Cassie will you do the disclaimer please?**

**Cassie: Sure Everlark-forever12 does not own adventure time Pendleton Ward does. Even though she wishes does.**

**Me: Thanks Cass you're the best**

**Now let's continue the story**

Chapter 2: Just a normal day again

Cassie's POV

After being in OOO for a day, I met all of Finn's closest friends including his adoptive brother Jake the dog.

The first time I met Jake it was really funny

Flashback

After arriving at Jake's house Finn knocked on the door, Jake answered the door.

"Hey Finn! I've missed you!" Jake shouted giving Finn a big hug.

"Hey buddy" Finn shouted too giving Jake a big hug too.

While they were saying hello I just stood there awkwardly.

"Oohh Finn you scored herself a lady but wait is it one of those fish creatures like Susan Strong? Finn I told you to stay away from those" Jake said now feeling my chin for something.

"Whoa I am not a fish creature I am a human" I said pulling Jake off me and giving him back to Finn.

"Well if you are human then Finn you aren't the last human!" Jake said excitedly. "Well come on in Cassie I want you to meet my girlfriend Lady Rainicorn and the pups TV, Jake JR, Viola, Charlie and Kil Kim Whan.

"AWWWWW they are so cute" I said with big wide eyes.

"Hello Finn and Cassie I presume" Lady said with a English translator which Jake attached to her neck.

I sat down next down and the pups came up to me and sat on my lap.

"Aw I love them I want little pups" I said with tears in my eyes by how cute they are.

"Well you are welcome over every day if you want to so you can take care of them" Lady said.

"Thank you I will come over as much as I can if you are not busy" I said.

Jake's POV

Jake and Finn's Conversation 

"Finn, do you like her?" I asked pretty sure of what the answer will be.

"I don't know, it isn't like FP or PB, her smile is gorgeous and how she acts just makes me want to grab her and kiss her" He said with his face in his hands with his knees up to his chest.

I have to say even though Finn has grown up a lot and he looks more masculine, he's still a little kid learning all of these emotions about being a teenager.

"Well its obvious you like her so don't go all out and say it just flirt with her a bit and see what happens" I said.

**(A/N I don't know any good dating advice, I do like one of my friends and everyone else says that he likes me too but that's the best I can give sorry!)**

"Ok let's go back out I want to talk to Cass" Finn said now a bit more calmed down.

When we got back both Cass and Lady were gone but there was a note on the door.

_Finn and Jake_

_Cassie wanted to go to Marceline's so I took her because it is getting dark_

_Love Lady and Cassie_

_P.S The pups are in the living room_

_XXXXOOO_

"So let's go over to Marcy's then" Finn said looking a bit disappointed that Cassie wasn't here.

I knew that these feelings that Finn is feeling for Cassie is not like Princess Bubblegum and Flame Princess.

Cassie's POV

Even though I have been in OOO for a couple of days I have been introduced to Princess Bubblegum and Marceline and everyone else who Finn is friends.

I met PB's assistant and I am going to make sure that I will never be left alone with him because he is freaky as hell!

I am currently at Marceline's house and even though I have known her for a couple of days I am friends with her she is exactly like a big sister to me.

"Hey Marcy can I sing a song if that's ok?" I asked her

"Yeah I guess are you good at singing?" She asked me.

"I don't know I guess, my two closest friends that I was a good singer" I said.

"Well go ahead" Marcy said.

**(A/N this is my own song I wrote by myself so don't steal it! And sorry if it isn't that good and if it sounds like other songs)**

_I was locked in darkness_

_But that was before you set me free_

_One look, one touch and I was free of darkness_

_Do you care? Like I do_

_These feelings make me spread my wings and fly off_

_Do you care?_

_I have always loved you without even knowing it_

_But now you set me free_

_Don't leave me tonight or never_

_I might be captured again_

_(Captured again)_

_So don't leave me ever_

I sang the song off the top of my head. I realized that it was about my crush at school halfly but more about Finn as I felt captured and unwelcome but now I feel at home.

"How was that?" I asked Marceline.

"Really good" She said a bit star struck.

"Am I a bad singer?" I asked a bit shy.

"No you're a really good singer" Marceline answered.

"Marcy are you home?" Called Finn while knocking on the door.

"No, could he have heard that? Please no" I prayed silently.

"Yeah It's open Cassie and Lady is also here" Marceline answered.

"Hey Marcy and Cassie and Lady" Finn said waling in with Jake.

He then gave me a hug which made my cheeks go the brightest colour of red.

I then saw out of the corner of my life Marceline gave me a wink and a cheeky smirk.

"H-Hey Finn" I stuttered still blushing.

"Well do you weenies want to go dinner with me cause I have a gig and I am bored?" Marceline asked.

"Ok is it ok if I can go back to the tree house to get dressed" I said looking down the clothes I'm wearing it was a pink t-shirt with the letters LOVE on it with grey shorts that reached mid-thigh.

"Sure I'll come around at 7:30" Marceline said.

"Ok we will see you then" Finn said grabbing my hand and sat on Jake who had stretched into a giant dog.

**A/N**

**Well I was going to include the dinner in this chapter but nah I already have got an idea where to go with this story for the next chapter and let's just say it might be left on a giant cliff-hanger **

**I am so glad that I have finished this chapter, I also updated Two Halves Become One last night too**

**Two updates in two nights WHOO!**

**Also it is holidays soon so I will be able to update the stories soon too!**

**Bye!**

**Also 200 views on all of my stories?!**

**Wow I am gobsmacked I started cheering when I saw that I never thought I would get there **

**Thank you so much!**


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